It is well known that a LED chip is a semiconductor element having high light emitting efficiency. Recently, the LED chip is widely used in various illumination applications because the LED chip is characterized in low consumption and high luminance in comparison with the conventional lamp.
Increase in the power and the distribution density of the LED chips to meet the illumination application needing high luminance is accompanied with a problem of heat accumulation in the LED chip. If the heat generated by the LED chip cannot be effectively dissipated, the heat will accumulate in the LED chip. As a result, the illumination performance of the LED chip will be seriously affected, and even it is possible to damage the LED chip and shorten the service duration of the LED chip.
As shown in FIG. 1, it is known that a LED chip package includes a LED chip 2, a metal lead frame 4, a holder 5 and a packaging material 6. The LED chip 2 is fixed on an insulating layer 3. In order to dissipate the heat generated by the LED chip, the insulating layer 3 is in contact with a copper substrate 11 serving as a heat sink by means of bonding or adhering. The heat sink may be formed by a silicon substrate or a ceramic substrate. The heat is dissipated through the copper substrate 11.
A similar package is described in US 2006/0138621A1 wherein the heat sink is made of copper or molybdenum.